Tyrosine phosphorylation of Blk and Fyn Src homology 2 domain-binding proteins occurs in response to antigen-receptor ligation in B cells and constitutively in pre-B cells

Proc Natl Acad Sci U S A. 1994 May 10;91(10):4204-8. doi: 10.1073/pnas.91.10.4204.

Abstract

Proteins that bind to discrete domains of the Blk, Fyn, Lyn, and Btk protein tyrosine kinases were examined in pre-B cells that had not been subjected to any external stimulation, as well as in nonstimulated and antigen-receptor-ligated B cells. Proteins that bind to the Src homology 2 domains of Blk and Fyn were identified in B cells that had been activated with anti-IgM but were not identified in unstimulated B cells. A number of Blk and Fyn Src homology 2 domain-binding phosphoproteins were also observed in pre-B cells that had not been stimulated in vitro. The phosphoproteins seen in activated B cells potentially represent substrates that play a role in the pathway of antigen-receptor-mediated signaling. Distinct signaling pathways involving distinguishable kinase substrates may be relevant in pre-B-cell-receptor-mediated cell survival during ontogeny. These results indirectly support models that predict constitutive ligand-independent signaling by the pre-antigen receptor during lymphoid ontogeny.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • B-Lymphocytes / immunology
  • B-Lymphocytes / metabolism*
  • Base Sequence
  • Cell Line
  • Conserved Sequence
  • DNA Primers
  • Glutathione Transferase / biosynthesis
  • Glutathione Transferase / metabolism
  • Immunoblotting
  • Mice
  • Molecular Sequence Data
  • Phosphoproteins / isolation & purification
  • Phosphoproteins / metabolism*
  • Phosphotyrosine
  • Polymerase Chain Reaction
  • Protein-Tyrosine Kinases / metabolism*
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-fyn
  • Receptors, Antigen, B-Cell / metabolism*
  • Recombinant Fusion Proteins / biosynthesis
  • Recombinant Fusion Proteins / metabolism
  • Restriction Mapping
  • Tyrosine / analogs & derivatives*
  • Tyrosine / analysis
  • Tyrosine / metabolism
  • src-Family Kinases*

Substances

  • DNA Primers
  • Phosphoproteins
  • Proto-Oncogene Proteins
  • Receptors, Antigen, B-Cell
  • Recombinant Fusion Proteins
  • Phosphotyrosine
  • Tyrosine
  • Glutathione Transferase
  • protein-tyrosine kinase p55(blk)
  • Protein-Tyrosine Kinases
  • Fyn protein, mouse
  • Proto-Oncogene Proteins c-fyn
  • src-Family Kinases